Effect of time and environment conditions on mechanical- chemical-morphological properties of conventional glass ionomer cements

Kamila Rosamilia Kantovitz, Joel Motta-júnior, Kelly Maria Silva Moreira, Daniela Dellosso Cibim, Gisele Maria Correr, Roberta Caroline Bruschi Alonso, Fernanda Miori Pascon e Regina Maria Puppin-rontani.

Introduction: The satisfactory performance of a restorative material when exposed to chemical challenge may be relevant for its clinical indication. Objective: This in vitro study investigated the effects of chemical challenge on compressive strength (CS), diametral tensile strength (DTS), surface roughness (R), surface hardness (H), fluoride release (F) and morphological characteristics (SEM) of popular restorative glass-ionomer cements (GICs). Methods: Maxxion R (MX) and Magic Glass (MG) were prepared according to the manufacturer's’ instructions. Cilindric-shaped (6 x 3 mm) and disc-shaped (4 x 2 mm) specimens were used for CS and for DTS, R, H, F and SEM tests, respectively. Specimens of each material were randomly distributed according to chemical challenge: Demineralization solution (DE; pH 4.3); Remineralization solution/artificial saliva (RE; pH 7.0). The specimens were individually immersed in 2 mL of the solutions, which were daily changed. After 15 days of storage, CS, DTS, R, H, F, and SEM analysis were performed. CS and DTS were evaluated using a universal testing machine; R was evaluated using a surface roughness-measuring instrument; and H, using a Knoop microhardness tester. Data were analyzed by ANOVA and Tukey’s tests ( =0.05). Results: Storage condition did not affect CS, DTS or R of both GICs. Before storage, MX showed H significantly higher than MG. However, after 15 days storage in both DE and RE solutions, there was no difference between materials. MG showed higher fluoride release than MX, in all evaluation periods and in both solutions. DE significantly reduced H and increased F of both materials. Conclusions: Chemical challenge promoted by DE increased degradation, reducing H and increasing F. RE did not affect the mechanical properties and surface characteristics of GICs.

Keywords: Glass ionomer cement. Compressive strength. Tensile strength. Hardness.

How to cite: Kantovitz KR, Motta-Júnior J, Moreira KMS, Cibim DD, Correr GM, Alonso RCB, et al. Effect of time and environment conditions on mechanical-chemical-morphological properties of conventional glass ionomer cements. J Clin Dent Res. 2019 Sep-Dec;16(3):106-20.

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